Wednesday, September 26, 2012

Defining functional shoulder range of motion for activities of daily living JSES

Defining functional shoulder range of motion for activities of daily living is the subject of an article just published in JSES. The authors did a splendid job of measuring the ranges of motion in a group of normal subjects using an electromagnetic tracking system. This is an important article in that it emphasizes that ranges of motion, such as 120 of flexion, 45 degrees of extension, 60 degrees of external rotation, 115 degrees of cross-body adduction, and 100 degrees of internal rotation, may be sufficient for many activities of daily living. In other words, it is not essential to achieve "180 degrees" for a shoulder to be functional. It may be more important to assess the shoulder in terms of what functions it can do, rather than in terms of its range of motion.

The results of this study can be compared to those published in Practical Evaluation and Management of the Shoulder. Chapter 2. In that chapter, range of motion was measured using sensors connected to pins drilled into the humerus and scapula of volunteers to make sure that the movement of soft tissues on the bones did not affect the position of surface mounted sensors. To seen an example, look at minute 6:31 of this video.

Here are two graphs comparing the data from the recent JSES paper with the data from the PEMS book.

We described the plane of elevation as shown below

In each plane we characterized the angle of elevation in terms of degrees and documented the plane and degrees of elevation for activities of daily living:

These data are remarkably similar to those in the recent JSES article.

We also described the maximal angles of elevation achieved in different planes:

The planes of elevation can be described by the use of global diagrams oriented to the plane of the body:

The positions of the arm for activities of daily living and for the maximal ranges of motion in the different planes can be shown on these diagrams:

The rotation of the forearm can also be shown on these diagrams:

As well as the path taken by the overarm throw:

These diagrams can also be used for explaining Codman's paradox:

For those interested in digging deeper, the PEMS book also provides analogous data on the movement of the humerus relative to the scapula. This is of some importance, in that most of our therapies are directed at improving the glenohumeral, rather than the scapulothoracic component of overall shoulder motion.